Symptom
When two ISR 4331s are in HSRP pair and the Active goes down, the Standby correctly becomes Active. When the Active comes back online and has the delay timers configured, the Active automatically preempts and takes over as the Active router. The router tables does not get a chance to fully converge and could potentially black hole traffic until its router table is rebuilt and begins to forward traffic. This behavior was observed on both IOSXE versions 16.6.7 and 16.9.4.
Conditions
ISR4331 on 16.6.7 or 16.9.4 in HSRP pair and the Active router goes offline and then comes back online. Condition can be replicated in a lab by directly connecting the two ISRs with a single linke and manually bouncing the ports.
